Existing optically-based sensors have a configuration whereby the optically activated sensor substance resides between an optical pump and a detector. FIG. 1 depicts such an optically-based sensor. The optical pump is often a light emitting diode (“LED”) or laser. The detector is often an array of detectors, such as a charge coupled device (often referenced as a “CCD”). FIG. 1 shows an example of such a prior art device. A sample to be analyzed is placed in contact with the sensor substance, and the light emitted from the sensor substance is received by the detector. The detector then sends a signal which may be analyzed to determine whether the sensor substance detected the analyte.
This geometry has advantages, but does not allow easy integration within a liquid environment. For example, the optical pump and the detector each may need to be independently sealed to protect them from a sample being analyzed. It would be better if the optical pump and the detector could be sealed as a single unit. Further, a frame is often employed to maintain the distance between the sensor substance and the detector. Requiring such a frame adds to manufacturing cost and may result in the sensor being relatively large.